Causation and non-reductive physicalism: from overdetermination to multiple realisability

Davies, Thomas James (2024). Causation and non-reductive physicalism: from overdetermination to multiple realisability. University of Birmingham. Ph.D.

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Abstract

The first of three papers tackles the argument from causal overdetermination. I begin with an elaboration of the causal overdetermination argument. Two premises of this argument are focussed upon: the causal closure premise and the overdetermination premise. Causal closure states that for every physical event with a cause, it has a sufficient physical cause. Overdetermination states that there is no widespread or systemic overdetermining of effects, with overdetermination defined as an instance where one effect has two or more causes where any individual cause would be sufficient to bring about the effect. Following this, I provide several assumptions which underwrite those premises: the causal relata assumption, the causal relation assumption, and the causal singularism assumption, which I refer to collectively as “the sparse view”. Then, several canonical and original arguments against the causal closure premise are outlined, and the ways in which these arguments involve rejection of the highlighted assumptions is brought to attention. Finally, I consider these assumptions as they pertain to the overdetermination premise. I offer a novel assumption, “notional ubiquitous overdetermination”, which supposes a number of sufficient causes across levels of reality for quotidian events. This is defended as an intuitive starting point in opposition to causal singularism, an assumption which prioritises physical causation and which I take to underline the intuitive force of the overdetermination premise.

My next paper concerns the exclusion argument against non-reductive physicalism, due to Kim. I summarise the exclusion argument, which concludes that mental properties are ruled out as causes under non-reductive physicalism under certain seemingly reasonable premises. The paper addresses the exclusion premise specifically, which holds that there cannot be both a sufficient mental and physical cause for some later event. I consider Edwards’ Dictum, holding there to be a tension between vertical determination and horizontal causation, as an intuitive basis for the exclusion principle. The basic idea is that we do not require a prior mental cause, M1, of some future mental effect, M2, where there is already a physical property giving rise to M2 at that time. I consider the basis of the Dictum at length and suggest a disanalogy between the original use of Edwards’ Dictum and its use in support of an exclusion principle for mental and physical events. With exclusion undermined, a novel model is presented which allows for autonomous mental causation of macrophysical or everyday events in line with our common-sense understanding. I draw upon work by List and Menzies, and Yablo, to show that mental causes are commensurate with certain effects in a way that microphysical putative causes are not. The other part of my model involves incorporating behaviours as commensurate with mental events such that we can assert that some prior mental cause leads to some behavioural, macrophysical event. With Edwards’ Dictum and Kim’s exclusion principle undermined earlier in the paper, this model can allow for mental causation at a higher level without excluding base-physical properties as the generative bases of all those mental and behavioural events. The final section of the paper addresses some potential objections to the model. Causation and dependence or generation are thus not in competition, and mental causation is preserved for the non-reductive physicalist.

My third and final paper likewise concerns non-reductive physicalism. Non-reductive physicalism is motivated by multiple realisability, which pushes physicalists away from type-identity given the possibility of multiple physical properties being co-extensive with the same mental property. I suggest that the failure of type-identity, coupled with a persisting philosophical commitment to the notion that mental properties are dependent on and nothing-over-and-above physical properties, leads to the adoption of a certain type of relation by non-reductive physicalists to characterise the mental-physical relation. I call such relations “thin non-identity”, since they either involve identity somewhere in their formulation- say an identity between causal powers rather than the properties themselves- or they risk dissolution into identity on close inspection. Multiple realisability concerns re-emerge for such positions, if this is right. I suggest that one can satisfy the dependence commitment without maintaining that mental properties are nothing-over-and-above physical properties, and provide reasons for supporting a loosened “Nothing-Left” constraint instead which maintains the intuitive appeal of nothing-over-and-above without overly constraining theory-building. Next, two proposed formulations of non-reductive physicalism are introduced with this loosened constraint in mind, and which construe the mental-physical relation as causal, though not diachronically causal. I show not only that such views, once elaborated, can maintain mental properties are wholly dependent upon physical properties in an intuitively satisfying way, but that such formulations avoid multiple realisability objections and carry various theoretical benefits that prior formulations of non-reductive physicalism lack. Non-reductive physicalism is thus protected from the threat of multiple realisability, and either of my proposed solutions are also shown to fit with the sort of causal solution to the exclusion problem posited in my second paper. My thesis concludes, then, with non-reductive physicalism protected from the overdetermination argument, the exclusion argument, and concerns about multiple realisability, along with novel models of both non-reductive causation and mental-physical relations.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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